This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-202607, filed Jul. 16, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a catheter inserted into, for example, a blood vessel for use and a method of manufacturing the catheter.
In general, in performing a selective angiography or angioplasty, used are, for example, an angiography catheter, a guiding catheter, a dilatation catheter and an embolotherapy catheter (microcatheter).
Such a catheter is required to exhibit an excellent operability to permit the catheter to be inserted promptly and with an ensured selectivity into vasculature of a fine complex pattern.
The catheter is also required to have an outer diameter as small as possible while ensuring a predetermined inner diameter in order to widen the range of selection in the insertion region, to alleviate strain given to the patient, and to improve the operability in inserting the catheter into, for example, a blood vessel.
The catheter is required to meet various operability including, for example, pushing capability (pushability) that the pushing force of the operator for moving forward the catheter within a blood vessel can be transmitted from the proximal end of the catheter to the distal end; torque transmitting capability (trackability) that the turning force applied to the proximal end of the catheter can be transmitted to the distal end without fail; the following capability that the catheter is capable of following smoothly and without fail the guide wire preceding the catheter within a curved blood vessel; and kink resistance that, even after the guide wire is withdrawn after the distal end of the catheter has reached a desired region, the catheter is not kinked in the curved portion of the blood vessel. The catheter is also required to exhibit safety that the distal end of the catheter does not damage the inner wall of the blood vessel.
In order to obtain a good pushability and a good torque transmitting capability, it is desirable for the catheter to be formed of a relatively hard material except the distal end portion. In order to obtain a good following capability and safety, it is desirable for the distal end portion of the catheter to be formed of a relatively soft material.
As a catheter meeting the above-noted requirements, a catheter prepared by joining unit tubes made of different materials disclosed in, for example, U.S. Pat. No. 5,792,124, and a catheter prepared by co-extruding a plurality of different kinds of resins, disclosed in, for example, U.S. Pat. No. 5,456,674, are known.
However, the catheter prepared by joining unit tubes made of different materials is likely to be cut away because of decrease in the bonding strength at the joining portion. To overcome this difficulty, it is necessary to increase the thickness of the tube, i.e., the difference between the inner and outer diameters of the tube, making it difficult to diminish the outer diameter of the tube. Also, stepped portions are formed on the outer surface in the joining portions, with the result that the inner wall of the blood vessel tends to be damaged when the catheter is inserted into the blood vessel. In addition, since the rigidity is rapidly changed in the joining portion, the catheter tends to be kinked at the joining portion. In other words, the catheter is not satisfactory in the kink resistance.
On the other hand, a costly manufacturing apparatus is required in the method of manufacturing a catheter by the co-extrusion of a plurality of different kinds of resins, making the method impractical.
An object of the present invention is to provide a catheter excellent in operability such as the pushability, the torque transmitting capability, the following capability and the kink resistance and a method of manufacturing the catheter that is advantageous in making the catheter small in its outer diameter.
According to a first aspect of the present invention, there is provided a method of manufacturing a catheter having a proximal end, a distal end and a tubular member defining an inner lumen extending between the proximal end and the distal end, the method comprising steps of: preparing a first linear member made of a first resin material and a second linear member made of a second resin material; disposing the first linear member in a dense spiral or mesh in a first region of the tubular member and in a sparse spiral or mesh in a second region of the tubular member; and disposing the second linear member in a sparse spiral or mesh in the first region of the tubular member and in a dense spiral or mesh in the second region of the tubular member.
The method of the present invention may further comprise steps of: disposing the first linear member in an intermediate region between the first and second regions in a spiral or mesh of a disposing density intermediate between the disposing densities in the first and second regions; and disposing the second linear member in an intermediate region between the first and second regions in a spiral or mesh of a disposing density intermediate between the disposing densities in the first and second regions.
In this case, the first region, the intermediate region and the second region are arranged in the order mentioned as viewed from the proximal end of the catheter.
To be more specific, the method of the present invention is performed by, for example, rotating the supply source of the first linear member and the supply source of the second linear member around the tubular member and by adjusting the relative rotating speeds of the supply sources of the first and second linear members so as to adjust the disposing densities of the first and second linear members on the tubular member.
In the method of the present invention, it is desirable for the first linear member to have a flexural rigidity higher than that of the second linear member.
The method of the present invention may further comprise steps of: melting at least partially the first and second linear members disposed on the tubular member so as to mix or fuse the first and second linear members; and solidifying the molten portion.
The method of the present invention may further comprise a step of covering the first and second linear members disposed on the tubular member with a heat shrinkable tube and heating the resultant product, thereby melting at least partially the first and second linear members so as to mix or fuse these first and second linear members and solidifying these first and second linear members.
The method of the present invention may further comprise a step of disposing the first linear member alone in a region on the side of the proximal end relative to the first region of the tubular member.
The method of the present invention may further comprise a step of disposing the second linear member alone in a region on the side of the distal end relative to the second region of the tubular member.
According to a second aspect of the present invention, there is provided a catheter having a proximal end, a distal end and a tubular member defining an inner lumen extending between the proximal end and the distal end, comprising: a first resin layer arranged in a first region of the tubular member and consisting of a first resin material disposed in a dense spiral or mesh and a second resin material disposed in a sparse spiral or mesh; and a second resin layer arranged in a second region of the tubular member and consisting of the second resin material disposed in a dense spiral or mesh and the first resin material disposed in a sparse spiral or mesh.
The catheter of the present invention may further comprise a resin layer arranged in an intermediate region between the first region and the second region of the tubular member and consisting of the first resin material disposed in a spiral or mesh of a disposing density intermediate between the disposing densities in the first region and the second region and the second resin material disposed in a spiral or mesh in a disposing density intermediate between the disposing densities in the first region and the second region.
In the catheter of the present invention, the first region, the intermediate region and the second region are arranged in the order mentioned as viewed from, for example, the proximal end of the tubular member.
In the catheter of the construction described above, it is possible for a resin layer consisting of the first resin material alone to be arranged in a region on the side of the proximal end relative to the first region of the tubular member. Also, in the catheter of the construction described above, it is possible for a resin layer formed of the second resin material alone to be arranged in a region on the side of the distal end relative to the second region of the tubular member.
In the catheter of the present invention, it is possible for second resin layers consisting of the second resin material disposed in a dense spiral or mesh and the first resin material disposed in a sparse spiral or mesh to be arranged in two second regions on the sides of the proximal end and the distal end, respectively, relative to the first region of the tubular member. In this case, the second region on the side of the proximal end, the first region and the second region on the side of the distal end are arranged in the order mentioned as viewed from the proximal end of the tubular member.
In the catheter of the construction described above, it is possible for a resin layer consisting of the first resin material alone to be arranged in a region on the side of the proximal end relative to the second region on the side of the proximal end. Also, in the catheter of the construction described above, it is possible for a resin layer formed of the second resin material alone to be arranged in a region on the side of the distal end relative to the second region on the side of the distal end.
In the catheter of the present invention, it is desirable for the first resin material to have a flexural rigidity higher than that of the second resin material.
In the catheter of the present invention, it is possible for the first and second resin layers to be formed of the first resin material and the second resin material that are melted at least partially so as to be mixed or fused and, then, solidified. In this case, it is possible for at least one of the first and second resin materials to be melted partially so as to retain the skeleton thereof.
In the catheter of the present invention, it is possible for the first and second resin layers to be formed in a region except the distal end portion of the tubular member.
The catheter of the present invention may further comprise a reinforcing layer made of a metal on the tubular member. It is desirable for the reinforcing layer to be consisted of a braided body of a metal wire or a metal ribbon. The catheter of the present invention may further comprise a low friction layer on the inner surface of the tubular member. The catheter of the present invention may further comprise an outer layer formed on the first and second resin layers.
Another method for manufacturing a catheter of the present invention comprises steps of: preparing a first linear member made of a first resin material, a second linear member made of a second resin material, and a mandrel; disposing the first linear member in the form of a dense spiral or mesh on a first region of the mandrel and in the form of a sparse spiral or mesh on a second region of the mandrel; disposing the second linear member in the form of a sparse spiral or mesh on the first region of the mandrel and in the form of a dense spiral or mesh on the second region of the mandrel; melting at least partially the first and second linear members disposed on the mandrel so as to mix or fuse the first and second members; solidifying these first and second linear members; and drawing out the mandrel, thereby forming a catheter comprising a resin layer having a proximal end and a distal end, and defining an inner lumen extending between the proximal end and the distal end.
Another catheter of the present invention comprises a resin layer having a proximal end and a distal end, and defining an inner lumen extending between the proximal end and the distal end, wherein a first region of the resin layer consists of a first resin layer constituted by a first resin material formed into a dense spiral or mesh and a second resin material formed into a sparse spiral or mesh, and a second region of the resin layer consists of a second resin layer constituted by the second resin material formed into a dense spiral or mesh and the first resin material formed into a sparse spiral or mesh.
According to the present invention, two kinds of resin materials differing from each other in properties are used for adjusting the disposing densities so as to provide a catheter having a flexural rigidity gradually diminished from the proximal end toward the distal end. The particular catheter exhibits excellent following capability, safety and kink resistance.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.